Sri Lanka → United Kingdom
Sri Lanka plugs
Type GUnited Kingdom plugs
Type GShared plug type: G
Compatibility: Compatible
Voltage — Sri Lanka 230V — United Kingdom 230V
Voltage is the same. Your devices should work normally.
Device compatibility (phones)
Phones almost always support 100–240V, so yours should work safely. Check your charger label to confirm.
You likely only need a plug adapter (if socket shapes differ). Voltage is close between these countries.